drivers: spi_mcux_lpspi: Fix DMA path on RT

Apparently, the previous change to fix the chip select only works on
some newer revisions of the LPSPI, and the behavior is different on
older parts like RT. For now put some #ifdef to keep the fixed CS on
MCXN but have the old behavior on RT and other platforms.

Signed-off-by: Declan Snyder <[email protected]>

Author: decsny

drivers/spi/spi_mcux_lpspi.c

@@ -483,7 +483,9 @@ static int transceive_dma(const struct device *dev, const struct spi_config *spi
 		return ret;
 	}
 
+#ifdef CONFIG_SOC_SERIES_MCXN
 	base->TCR |= LPSPI_TCR_CONT_MASK;
+#endif
 
 	/* DMA is fast enough watermarks are not required */
 	LPSPI_SetFifoWatermarks(base, 0U, 0U);
@@ -500,9 +502,11 @@ static int transceive_dma(const struct device *dev, const struct spi_config *spi
 				goto out;
 			}
 
+#ifdef CONFIG_SOC_SERIES_MCXN
 			while (!(LPSPI_GetStatusFlags(base) & kLPSPI_TxDataRequestFlag)) {
 				/* wait until previous tx finished */
 			}
+#endif
 
 			/* Enable DMA Requests */
 			LPSPI_EnableDMA(base, kLPSPI_TxDmaEnable | kLPSPI_RxDmaEnable);
@@ -513,6 +517,12 @@ static int transceive_dma(const struct device *dev, const struct spi_config *spi
 				goto out;
 			}
 
+#ifndef CONFIG_SOC_SERIES_MCXN
+			while ((LPSPI_GetStatusFlags(base) & kLPSPI_ModuleBusyFlag)) {
+				/* wait until module is idle */
+			}
+#endif
+
 			/* Disable DMA */
 			LPSPI_DisableDMA(base, kLPSPI_TxDmaEnable | kLPSPI_RxDmaEnable);